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Deformation of Grímsvötn volcano, Iceland: 1998 eruption and subsequent inflation

2003; American Geophysical Union; Volume: 30; Issue: 4 Linguagem: Inglês

10.1029/2002gl016460

1944-8007

Erik Sturkell, Páll Einarsson, Freysteinn Sigmundsson, Sigrún Hreinsdóttir, Halldór Geirsson,

Geological and Geochemical Analysis

Grímsvötn is a subglacial volcano, under the Vatnajökull ice cap at the center of the Icelandic hotspot. This highly active volcano erupted in December 1998. GPS measurements at a single station on a nunatak at the caldera rim were made 7 times during 1992–2001. The measurements prior to the 1998 eruption reveal pre‐eruption inflation, but subsidence of more than 15 cm was measured during the eruption. Following the eruption, re‐inflation occurred initially, at a rate of 20 mm/month, then declined to 5 mm/month. Measurements were fitted to a Mogi model, assuming that the source was located under the center of the Grímsvötn caldera complex. Results indicate a source depth of at least 1.6‐km. The calculated amount of magma outflow during the eruption is comparable to field estimates of the erupted volume. Grímsvötn continues to inflate, but has not reached its 1998 pre‐eruption level.